Complications Of MCAD Deficiency

MCAD deficiency is the condition in which the enzyme required for oxidation of fatty acids is absent in the body. This condition is genetically inherited and is inherited in autosomal recessive manner. Various complications develop due to improper management of the disease.

Complications Of MCAD Deficiency

Nervous Complications: The untreated and unmanaged MCAD deficiency may cause seizures in conditions where the body lacks energy. The seizures are mainly due to lack of energy that causes electrical disturbances in brain. Further, various other CNS related symptoms such as vomiting, dizziness occurs, and the person may go into coma.

Hepatic Complications: Hepatic disorders are the major complication in patients with MCAD deficiency. It is due to the fact that the process of gluconeogenesis is halted in the liver due to the deficiency of enzyme and the situation is further complicated by the accumulation of fatty acids inside the hepatic cells. Hepatomegaly may also develop.

Respiratory Problems: Due to lack of energy in the body, the body would be unable to perform routine activities. This may lead to breathing problems and if not managed at an early stage, the condition may further complicate to cause respiratory arrest.

Prepubertal Obesity: Patients with MCAD deficiency may develop prepubertal obesity, a condition which is difficult to treat.

Muscular Abnormalities: Muscles of the body requires continuous energy, especially smooth and cardiac muscles. Any lack of energy in the muscles may cause dysfunction of systems such as gastrointestinal system and cardiovascular system.

Sudden Infant Death Syndrome: SIDS is the syndrome caused due to MCAD deficiency in which sudden death occurs even due to minor illness.

MCAD Deficiency

MCAD, also known as Medium-chain acyl-CoA dehydrogenase, is an enzyme used in the oxidation of fatty acids. This enzyme helps in the conversion of medium chain fatty acids to acetyl Co-enzyme. This acetyl co-enzyme is an important ingredient in the process of gluconeogenesis i.e. formation of glucose. It is most common fatty acid oxidation disorder and is under the category of inborn error of metabolism. Thus, in case of deprivation of glucose in the body, the body is unable to produce the glucose from fats through gluconeogenesis. This leads to the reduction of glucose to dangerously low level and the condition of hypoglycemia develops.

Further, the blockage of gluconeogenesis and the conversion of medium chain fatty acids to small chain fatty acids cause the reduction of ketones, leading to the hypoketotic condition. Further, the accumulation of fatty acids accumulates in the liver cells leading to liver disorders. The glucose levels are at such low levels that the body is completely exhausted of energy leading to severe effect on nervous system, hepatic system, respiratory system and also lead to sudden death. The condition is more pronounced in the cases of fasting, illness, vomiting and in other conditions when the body needs excess energy. Many individuals remain asymptomatic throughout their life due to the reason that they never encountered situations when they need high levels of energy. The gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources such as fats and amino acids. This process is initiated when the body needs excess energy and the glucose levels in the body are unable to provide the required energy.


MCAD deficiency is an autosomal recessive character. The individual should inherit copies from both the parents to develop this condition. The gene which gets mutated in this condition is ACADM. The disease is relatively more prevalent in Northern European Caucasians and the prevalence of the disease is around 1in 4000 to 1 in 17000. The disease is not wholly dependent upon the genotype rather the occurrence of the symptoms also depends upon the environmental factors such as the exposure to the conditions requiring additional energy.


Most of the complications associated with MCAD deficiency is due to severe lack of energy in various conditions such as fasting, vomiting and illness such as infection. The complications include respiratory failure, cardiac arrest, nervous system abnormalities and sudden death.

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Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:December 4, 2018

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